This weekend’s historic tornado outbreak saw at least 50 twisters, many of them fatal, in Kentucky, Arkansas and Illinois. Hundreds of buildings were destroyed and millions remain without power. The weather pattern is changing into a powerful blocking high to the East, which will deliver a record-breaking heatwave in the middle of this week. To the West, another winter storm is expected to lash the Rockies and the Midwest into the Great Lakes, bringing snow to the north and windy conditions throughout the central United States.
Unfortunately, the death toll from the tornado outbreak is likely higher than 100 as rescuers examine tornado wreckage and search for missing people. Twisters have already killed more than 80 people in Kentucky, with the worst damage in Mayfield.
So far, there have been 94 confirmed deaths. 6 people were killed by lightning in Illinois, 4 in Tennessee and 2 in Arkansas. 1 was killed in Missouri. According to Edwardsville police, the 6 victims in Illinois were killed when an Amazon warehouse collapsed.
HISTORIC TORNADO OUTBREAK HIT ARKANSAS MISSOURI TENNESSEE AND KENTUCKY
Friday night’s tornado outbreak, which lasted approximately 11 hours, ravaged large swathes of east-central U.S. Leaving 50 tornado reports. There have been 50 tornado reports. 23 tornado paths have been surveyed. This has resulted in 5 EF3, 8 EF2, 7, EF1, and 3 EF0. The damage survey along the paths for the strongest tornadoes is still ongoing and could take several days to complete as the destruction is devastating.
The attached composite radar picture above shows that the Quad State storm was a cyclic-tornadic supercell. It originated SW of Little Rock AR and intensified while moving into the NE Arkansas. SE Missouri, NW Tennessee, and Kentucky. The supercell was active for more than 11 hours. It produced many tornadoes along its 600-mile route.
The path of destruction was approximately 227 miles long, making it one of the most dangerous tornadoes to be born from this supercell. The tornado travelled across four states, touching down on 200 miles in Kentucky. It started in northeast Arkansas, crossed into Missouri’s extreme southeast, and then moved into Tennessee. The tornado then reached Kentucky and caused havoc in many towns.
NOAA scientists are currently in the field conducting damage surveys along the tornado track. According to preliminary data, this event may have produced one the longest-track tornadoes ever recorded in U.S. history. It may have beat the famous Tri-state tornado outbreak of March 18, 1925, which traveled 219 miles (352km) in just 3.5 hours. The Tri-State Tornado, which swept through Missouri, Illinois and Indiana, left nearly 700 dead and is still the longest-running tornado.
Below is a snapshot of the historic tornado outbreak of December 10, 2017 in the United States. Tens of tornado warnings were issued in the affected states. Twisters have been reported by red triangles. You can see how long the tracks are. Tornado warnings run along them from Arkansas and Missouri to east-northeast, ending at Illinois, Kentucky and Tennessee.
Storm Prediction Center (SPC), which had their exact convective outlooks within the last 48 hours before the severe weather event occurred, was able to very accurately forecast it.
The nation has been hit with cold weather, which poses an additional threat to those affected. The weather is changing, however, as warmer temperatures are expected to be in the coming days.
POWERFUL HIGH ESTABLISHES, BRINGS EXTREMELY STABLE AND EXTREMELY WINDY WEATHER FOR MANY THIS WOKE
The weather pattern is now hinting towards a record-breaking heatwave in the central United States after a major winter storm brought severe weather to the Ohio Valley. The unseasonable heat will spread from Texas to Minnesota in the North, and across the Mississippi Valley to Ohio Valley. Also, further north into southern Canada.
Significant warmth will follow the weather pattern shift with a powerful blocking high developing across the eastern U.S.A and the deep trough emerging onto the West Coast. A classic dipole pattern will continue for several more days before another winter storm roars across the Rockies into Canada and the Great Lakes.
A warm and unseasonably dry period will occur under the ridge. This will provide relief from the tornadoes that devastated the region over the weekend. The temperature will be extremely warm, even more than 40 °F above normal for mid-December across several states.
As temperatures are expected to be more typical of September and October, it will feel more like fall is coming back.
The winter heatwave that is coming will be even more intense and challenging than the warmth experienced last week in the central U.S., setting high temperatures daily and challenging many. A heatwave is defined by the National Weather Service as a period of extremely warm weather that lasts at least two consecutive days.
You can probably recall hearing the term heat-dome quite often last summer. It was the dominant feature for summer 2021 in both North America and Europe, leading to deadly heatwaves as well as wildfires. It is the term to blame in this wild year of weather, and here’s why.
HEAT DOME CAN ADD INTENSE HEATWAVE, ALSO IN WINTER SEASON.
The blocking High pattern is located under the upper-level Ridge, also known as the blocking High. heat domeThey occur quite frequently. This type of weather pattern can bring record-breaking temperatures to the region below, regardless of the season. A heat dome refers to a large area of high pressure parks that covers a large part of the continent. It can last for days or even weeks, most often in summer, but sometimes even in winter.
The heat dome works in the same way as a lid on an oven. The large dome traps a significant warmer air mass underneath, making it extreme at the lowest elevations. This creates stable weather, often with very little chance of precipitation or even clouds. This is possible because of the heat dome’s ability to sink air parcels, allowing air mass warmth a lot.
The daily maximum and average temperatures are usually well above the average temperature under the heat dome and often challenge or break existing heat records. This is exactly what will happen this week with a strong, dome expected to form beneath the powerful upper high.
It is important to note that the heat dome is often blamed for causing deadly heatwaves all over the globe.
EXTREMELY HIGH TEMPERATURES COULD SMASH ALL-TIME HEAT RECORDS
St. Louis (MO) tied its all-time highest temperature for December on the 3rd, ending at 76 °F, breaking the 70+-year-old record. The heat record could be broken once more by the extreme heat that is expected in the days ahead. Central Missouri could reach the mid- to upper 70s again.
Chicago could reach the mid- to upper 60s Wednesday with temperatures reaching the low 70s in the southern and western parts of Illinois. The temperature records for December 15th were easily broken.
Actually, the warm spell will be so intense towards the north, Chicago might be challenging its all-time December’s heat record of 71 °F, set back on Dec 2nd, 1981. The large city often battles with the cool breeze from Lake Michigan, but with strong enough southwesterly winds, temperatures could break above the 70 °F mark on Wednesday.
Temperatures will rise in areas that were recently buried by snow, such as the northern Plains or Upper Midwest. Snow will melt quickly due to the significant warmth. Temperatures will rise to the mid-60s to upper 70s by Wednesday.
Temperatures in the 60s are predicted for Nebraska, Iowa, Minnesota, Wisconsin, and Wisconsin. These states will experience temperatures that are unprecedented in December, including Des Moines, Iowa, Minnesota, and Wisconsin. Temperatures could reach the mid-70s to mid-week, setting new records if the forecast is correct. Similar record-breaking temperatures are also possible in Kansas City (MO), Wednesday.
Wednesday’s temperature anomaly of 2m is truly extraordinary. Temperatures across Oklahoma, Kansas, Missouri, parts of Nebraska, Iowa, Illinois, southern Minnesota, and southern Wisconsin will be 30 to more than 35 °F above normal. That’s really extreme and that is why we are about to challenge those heat records quite likely.
Thursday will be even more warm from Missouri to Illinois, Wisconsin, and temperatures anomalies will rise even higher than they were a day ago. If those nearly 40 °F are above normal verify, all-time records will be easily shattered. Notice how extreme warmth also spreads into southern Canada on both days, 25 to more than 30 °F above normal is forecast. It will be much more warm in the South, with temperatures reaching the mid-80s in Texas.
The heatwave will be concentrated in the central U.S. but the warmth will expand to the east. High daytime temperatures could also be pushed towards the East Coast and Northeast U.S. during the second week. Temperatures could rise to the mid- to upper 60s and possibly even the low 70s by the weekend.
The East Coast already saw significant warmth this weekend, breaking old records in New York, Washington D.C. and Philadelphia.
THE SIGNIFICANT WINDS FOR THE SOUTHEAST WILL BE BRINGED BY THE NEXT WINTER STORM.
However, the powerful upper Ridge (High) won’t last more than a few short days. The progressive weather pattern across North America is not ending this month. The deep low that will make its way to the West Coast this week in the early hours of the week will continue east into the Contiguous U.S. and create another significant winter storm. The chart below shows how the ridge is replaced by the new trough.
The heat dome and the parent high gradually expands into the Northeast U.S.A and eastern Canada after Wednesday. This will push temperatures higher. You can also see how a strong Ridge also forms over the northern Pacific. This will help push colder air mass and the West Coast Trough into the western CONUS.
The Rockies trough progresses, creating a secondary low, or surface depression, along eastern mountain chains by Tuesday night. It intensifies into Wednesday, and then slowly expands towards Great Plains.
The pressure at this surface low will increase by about 12-15 mbar, while the center moves towards Wednesday night’s Upper Midwest. Now consider how strong the upper High will appear to the east. This calls for a very intense jet stream between these two large-scale features. These winds will also affect the Plains, as they will be affecting the lower levels.
The pressure energy will produce a broad band of particularly strong winds that will blow off the eastern Rockies to the Great Plains. The winds will first intensify over the High Plains and then spread into the Central Plains during Wednesday’s day. Meanwhile, the low tracks to northeast will be affected. Damaging winds are possible from the southern Rockies and Upper Midwest. They can extend over more than a 1000-mile stretch (from New Mexico through Iowa and farther northeast) across the central regions of the country.
Many areas will see winds gusting between 50-70 mph, including Chicago, on Wednesday night. This will happen shortly after the heatwave has reached its peak. Winds could cause damage to trees and power outages. This strong wind can cause the greatest danger to high-profile vehicles that travel across the Plains. The risk of roll-overs is high.
As the winds accelerate down the slopes towards the Plains, the most intense gusts are likely to develop along the Front Range of the Rockies of Colorado. They could easily reach 100 mph.
When the low crosses the Upper Midwest towards south Canada by Thursday, gusty wind will spread eastward and reach the Great Lakes, reaching Indianapolis, and Detroit. As low continues to deepen, strong gusty winds will spread throughout southern Ontario.
The cold front associated to this low will also bring additional storms, possibly even severe, from eastern Texas through Mississippi and Ohio Valley on Thursday night. Despite the absence of strong thunderstorms, severe winds could cause additional damage in the areas that were severely hit Friday night.
The front will gradually move east-southeast from overnight to Friday, bringing heavy rain and stormy weather across the Southeast U.S.
INTENSE Winter Storm BRINGS LOTS OF SNOW TO THE ROCKIES
Significant snowfall will be caused by a new winter storm that is moving from the West Coast to the Rockies. First, intense and excessive snowfall will blast across Nevada, Utah, and northern Arizona on Tuesday through Wednesday morning, with a forecasted *huge* amount of snow across the mountain tops. Snow heights will vary by several feet.
The winter storm intensifying through Wednesday means that the heaviest snowfall will be in Colorado and Wyoming, but also northern New Mexico. Expect heavy snowfall along the leading cold front.
Further north, the winter storm could bring new snow to parts of the Upper Midwest from Wednesday night through Thursday. The amounts should not be too large, according to recent forecast models.
This is because the low will not be as intense as usual, and that moisture conditions will be poor under the strong southwesterly stream. The severe wind that will blow across the Plains or Midwest will be exacerbated by the high pressure difference.
The intense wind field created by this storm will produce the highest amount snow accumulation across the Rockies, specifically in mountain ranges with the most intense orographic features. This is especially true for the Sierra Nevada Mountains, as you can see from the chart.
The snow amounts for the next five days are quite impressive. It is possible to get more than 85 inches (or 7 feet) of fresh snow. Avalanches will be a problem in these areas.
Our thoughts are with all those who were affected by the recent hurricane. Keep safe!
Images used in this article were supplied by Wxcharts and Tropical Tidbits.
SEE ALSO – these days, the peak of the Geminid Meteor Shower occurs. Enjoy the amazing celestial show.
Source: Severe Weather